Loans - Summary of Troubled Debt Restructurings, Included in Covered Loans, by Collateral Types (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 Contract	Dec. 31, 2013 Contract	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 21,100	$ 20,900	$ 20,600
Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	9,221	8,409	10,253
Accruing Loans [Member] | Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	87	76	70	70
Troubled debt restructuring loans	9,221	8,409	10,253	10,253
Accruing Loans [Member] | Covered Loans [Member] | Raw Land [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts				1
Troubled debt restructuring loans				366
Accruing Loans [Member] | Covered Loans [Member] | Hotel & Motel [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1		1
Troubled debt restructuring loans	175	172		170
Accruing Loans [Member] | Covered Loans [Member] | Office [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Troubled debt restructuring loans	488
Accruing Loans [Member] | Covered Loans [Member] | Retail, Including Strip Centers [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	2		2
Troubled debt restructuring loans	280	283		277
Accruing Loans [Member] | Covered Loans [Member] | 1-4 Family Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	83	73		65
Troubled debt restructuring loans	8,278	7,954		9,400
Accruing Loans [Member] | Covered Loans [Member] | Automobile/Equipment/Inventory [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts				1
Troubled debt restructuring loans				40
Non-Accruing Loans [Member] | Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	12	11	4	4
Troubled debt restructuring loans	597	686	151	151
Non-Accruing Loans [Member] | Covered Loans [Member] | Raw Land [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	1		1
Troubled debt restructuring loans	38	16		10
Non-Accruing Loans [Member] | Covered Loans [Member] | Retail, Including Strip Centers [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1		1
Troubled debt restructuring loans	128	134		19
Non-Accruing Loans [Member] | Covered Loans [Member] | 1-4 Family Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8	7		2
Troubled debt restructuring loans	407	469		122
Non-Accruing Loans [Member] | Covered Loans [Member] | Automobile/Equipment/Inventory [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	2
Troubled debt restructuring loans	$ 24	$ 67